73 lines
1.5 KiB
C++
73 lines
1.5 KiB
C++
// Copyright (C) 2015 Jérôme Leclercq
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// This file is part of the "Nazara Engine - Core module"
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// For conditions of distribution and use, see copyright notice in Config.hpp
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#include <Nazara/Core/Hash/Fletcher16.hpp>
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#include <Nazara/Core/Endianness.hpp>
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#include <Nazara/Core/Debug.hpp>
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struct NzHashFletcher16_state
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{
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nzUInt16 sum1;
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nzUInt16 sum2;
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};
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NzHashFletcher16::NzHashFletcher16()
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{
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m_state = new NzHashFletcher16_state;
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}
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NzHashFletcher16::~NzHashFletcher16()
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{
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delete m_state;
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}
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void NzHashFletcher16::Append(const nzUInt8* data, unsigned int len)
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{
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while (len)
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{
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unsigned int tlen = std::min(len, 21U);
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len -= tlen;
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do
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{
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m_state->sum1 += *data++;
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m_state->sum2 += m_state->sum1;
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}
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while (--tlen);
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m_state->sum1 = (m_state->sum1 & 0xff) + (m_state->sum1 >> 8);
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m_state->sum2 = (m_state->sum2 & 0xff) + (m_state->sum2 >> 8);
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}
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}
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void NzHashFletcher16::Begin()
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{
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m_state->sum1 = 0xff;
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m_state->sum2 = 0xff;
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}
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NzHashDigest NzHashFletcher16::End()
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{
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m_state->sum1 = (m_state->sum1 & 0xff) + (m_state->sum1 >> 8);
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m_state->sum2 = (m_state->sum2 & 0xff) + (m_state->sum2 >> 8);
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nzUInt32 fletcher = (m_state->sum2 << 8) | m_state->sum1;
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#ifdef NAZARA_BIG_ENDIAN
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NzByteSwap(&fletcher, sizeof(nzUInt32));
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#endif
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return NzHashDigest(GetHashName(), reinterpret_cast<nzUInt8*>(&fletcher), 2);
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}
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unsigned int NzHashFletcher16::GetDigestLength()
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{
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return 2;
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}
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NzString NzHashFletcher16::GetHashName()
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{
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static NzString hashName = "Fletcher16";
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return hashName;
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}
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